It was less ideal for the people whose front lawns were suddenly thronged with mating birds and associated debris. "When we got out there, many egrets were well-established and nesting, and there were heavy accumulation of bird droppings, both fecal material and regurgitation," said Carrollton's environmental director, Scott Hudson. Standing in the neighborhood, one could hear the regular plip plop of viscous liquid striking the ground.

There was no rain to speak of that summer, so the droppings simply accumulated on sidewalks and in front yards, and with the heat came the penetrating smell of ammonia. Hudson said that homeowners couldn't so much as walk outside and retrieve their mail without donning an umbrella and designated shit-wading shoes.

City workers patrolled the neighborhood three times a day, searching for dead and injured birds; the latter they would transfer to wildlife rehabilitation centers. They found about 350 of each that summer.

The city's response was complicated by the Federal Migratory Bird Treaty Act, which offers broad protections for winged travelers including a provision making it a crime to disturb a nest where eggs have been laid. So, the city and neighborhood residents had to wait until the egrets left of their own accord, which took about five months.

But migratory birds, once they've found a suitable nesting place, have a tendency to return year after year to lay their eggs, meaning that Carrollton residents were in for a lifetime of wading through bird crap if they and the city didn't do something to make their lawns less attractive for egrets.

So the city armed itself with starter pistols that fire "screamers" and "bangers," which make loud screaming and banging noises, respectively, and six propane cannons that Hudson describes as "very loud." Residents have also trimmed their trees, making the canopy less inviting, and are on a perennial crusade to remove any hint of an egret nest before an egg can be laid there. It's sort of like a hyper-vigilant crime watch, only the thing they're watching for are federally protected bird species.

Hudson counts the summer of 2012 as a success. Only a dozen nesting pairs of egrets set up shop in the city, down considerably from the 2,000 or so birds that had nested in the north Carrollton neighborhood the previous year.

But the battle is far from won. Hudson has already spotted some yellow-crowned night herons, which serve as a leading indicator for an egret invasion, and the city is redoubling efforts to let the birds know they're not welcome. He expects it to take another year or two before they permanently get the message and find somewhere else to mate.

Neighbors seem willing to put up with however many screamers and bangers and cannons the city wants to shoot off, so long as it'll keep the birds away. It's a small price to pay to not have to wade through ankle-deep feces.